High-temperature furnace for melting materials in space

ABSTRACT

An electrically powered furnace for melting high-melting point materials in the vacuum and zero gravity environment of space comprising an alumina crucible, cylindrical in shape, and enclosing a cylindrical tantalum sample holder that contains the sample to be melted. The crucible is surrounded by concentric cylindrical enclosures made of polished sheet molybdenum. The sample holder is clamped between a pair of round plates and a pair of alignment bolts are joined to the circular plates and extend along the longitudinal axis of the furnace through the end covers of the crucible and surrounding concentric enclosures.

United States Patent Rasquin 1151 3,647,924 1 51 Mar.7, 1972 [72]inventor:

[54] HIGH-TEMPERATURE FURNACE FOR MELTING MATERIALS IN SPACE John R.Rasquin, Madison, Ala.

[73] Assignee: The United States of America as represented by theAdministrator of the National Aeronautics and Space Administration 221Filed: Feb. 12,1971

211 Appl.No.: 114,848

. [52] US. Cl ..l3/20, 13/31 [5 1] Int. Cl. [58] Field otSearch ..l3/20,21; 219/343, 349, 424

[56] References Cited UNITED STATES PATENTS 3,170,018 2/l965 Lewis..l3/3l 3,456,935 7/1969 Bornor ..l3/3l X Primary Examiner-Bernard A.Gilheany Assistant Examiner-Roy N. Envall, .l r.

Attorney-L. D. Wofi'ord, Jr., W. H. Riggins and John R. Manning [57]ABSTRACT An electrically powered furnace for melting high-melting pointmaterials in the vacuum and zero gravity environment of space comprisingan alumina crucible, cylindrical in shape,

and enclosing a cylindrical tantalum'sample holder that contains thesample to be melted. The crucible is surrounded by concentriccylindrical enclosures made of polished sheet molybdenum. The sampleholder is clamped between a pair of round plates and a pair of alignmentbolts are joined to the circular plates and extend along thelongitudinal axis of the furnace through the end covers of the crucibleand surrounding concentric enclosures.

8 Claims, 2 Drawing Figures HIGH-TEMPERATURE FURNACE FOR MELTINGMATERIALS IN SPACE ORIGIN OF THE INVENTION The invention describedherein was made by an employee of the United States Government and maybe manufactured and used by or for the Government for governmentalpurposes without the payment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION aboard earth-orbiting workshops,laboratories and space stations that will remain in earth orbit for longperiods. I

Included in the projects to be undertaken in earth orbit are experimentsrelating to manufacturing .in space. The advantages of using the spaceenvironment for carrying out certain manufacturing processes is wellrecognized andit is anticipated that some day many unique products willbe made in space. These products will be made by processing materials inthe fluid-state since itis in this state thatmaterials will be affectedby the vacuum and zero gravity condition in space.

In conducting experiments to observe and analyze the behavior of variousmaterials in space and thereby gain knowledge that will contribute tothe developmentof space manufacturing, furnace devices capable ofmelting the materials under study will be needed aboard theorbitingzspace vehicles. Such a furnace device should be highlyefticientso as not to require undue power, andthe furnace must beconstructed so as to not be impaired by.the high 'gforces experiencedduring certain phases of a space flight, for example, the launch phase.v

Although high temperature fumacesof various'designs are known, they arenot deemed to have thestructural rigidity and performance efficiencyrequired for use in a space facility.

SUMMARY OF THE INVENTION The invention comprises an electrically poweredfurnace for melting materials in the vacuum and zero gravity environmentof space. Thefurnace includes a crucible of refractory materialenclosing a sample holder adapted for containing the sample to bemelted. The crucible is surrounded by a plurality of spaced,concentrically related, polishedsheet enclosures, preferably ofmolybdenum, for preventing radiation loss from the'crucible. To providefirm support for'all the partsof the furnace and insure'thatthe'fumacewill'withstand high 3" forces the sample holder is clamped between apair of opposed plates and a pair of alignment bolts are joinedtotheplates and extend along the longitudinal axis of the furnace'throughopposite ends of the crucible *andpolishedsheet enclosures.'The

perature furnace for installation on *aspace vehicle and con-' structedsothat itwill withstand the high g" forcesattendant to certain phases ofspace flight.

These and other objects and advantages of the invention will becomeapparent upon-reference to the following specification, attendantclaims-and drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG; I is a vertical sectional view ofa high temperature furnace embodying the invention.

FIG. 2 is a sectional view taken along line 2-2 of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT :Referringto FIGS. 1 and 2,therein is shown a high tempera ture furnace 11 particularly adapted forinstallation on a spacecraft for melting samples of high-melting pointmaterials in the vacuum and zero gravity environment of space. Thefurnace 11 comprises an alumina cylindrical crucible 13 locatedcentrally of the furnace. The crucible has an integral bottom 15 and aseparate cover 17 fitted and joined to the main body of the crucible atthe upper end. Formed in the opposite end edges of the crucible 13 are aseries of vertical slots\19 arranged in spaced pairs to receive tungstenelectric resistance heating wire 23 that is looped around spacedsupports 25 between the slots 19. In the embodiment illustrated the wiresupports 25 are provided every radially and the supports at one end ofthe crucible are staggered relative to the supports vat the other endthereof. The wire is. arranged around the crucible 13 extendingdiagonally between upper and lower ends and being looped aroundthesupports 25, alternately, at the upperrand lower ends. Lead wires 27 forthe heating wire 23 extend from a power source .(not shown) and enterthe crucible l3;through a double-bore alumina tube 29 that is bonded inan opening 33 by a temperature-resistant cement.

.Another tube 29 is sealed in an opening 34 at the lower end of thecrucible for receiving lead wires 35 of athermocouple 37 associated withan indicator (not shown)for indicating temperaturewithinthe crucible.13.

*Surroundingthe crucible '13 are fourconcentrically related cylinders41, 43,45 and 47 of uniformly increasing diameter and length. Thecylinders are provided, respectively, with circular end covers 49, 51,53 and 55 that fit telescopically over the ends of the cylinders. Thecylinders and covers are made of polished :sheet molybdenum .thatreflect heat to prevent radiationlossafrom the crucible 13. The coversare not sealed to the cylindersso.that gas-trapped within each of thecylinders will escapewhenthe furnace is placedin a vacuum en--vironment..and:thereby assure against convection heat loss .betweenthecylinders and the crucible. The alumina tubes 29 :material'such as.glass for example. The sample is indicated in phantom linesin;its.solid.state and a spherical mass 67 represents the sample after being melted.Surrounding the sample 65 is a carbon cylinder 69 and end covers 71.Each of "the;carbon end covers71has-a central pointed projection 73tthabengagesthe sample 65-to support the sample until it is meltedfiwhenthe sample is melted itwill have no tendency to adhere tosthe carbon butwill. readily-"pull away from the carbon projections 73,.and form thesphere 67 without contamination-ofithe sample.

The-sample holder 61 is clamped-between a lower circular plate' 75 andanpupper'circular plate 77. Each of the plates are made of molybdenumandwthe lower plate 75 hasa circular -recess79therein that receives thelower end of the sample holder6l. Three molybdenum. clamping'bolts8leach have threaded. end portions :83 of reduced diameter extendingthrough vertically alignedholes' 85 -in the upper and lower plates. Nuts91 are used in clamping thesample holder 61 firmlybetween-theplates'75and-77.

Joined to eachof the plates'75 and 77 is a molybdenum bolt 93. The bolts93 are'locatedonthe vertical orlongitudinal axis of the furnace l 1 .andhave athreaded portion 95 screwed into athreaded hole 97in the center ofthe plates75and 77. The

and 77 through vertically aligned holes 99 in the top and bottom of thecrucible 13 and in the top and bottom covers of the cylinders 41, 43,45, and 47. Each bolt 93 has an unthreaded portion 101 of increaseddiameter that provides a spacer between the respective plates 75 and 77and the upper and lower ends of the crucible 13. Spacers in the form ofmolybdenum nuts 103 threaded on the bolts 93 are also provided betweenthe upper and lower ends of the crucible l3 and between the respectiveadjacent covers 49, 51, 53 and 55. Nuts 103 arealso threaded on thebolts 93 against the outer surfaces of the covers 55.

The furnace 11 may be mounted in a spacecraft in the manner desired andmay be enclosed in a chamber 105 (indicated in phantom line) that is putin communication, selectively, with the vacuum environment of space.Mounting elements 107 may be attached to the bolts 93 and to the chamber105.

The high temperature furnace disclosed herein is extremely efficient inthat heat losses from the crucible are minimal and the describedstructure of the furnace makes it uniquely sturdy and resistant todamage from subjection to high g forces.

1 claim:

1. A furnace for melting materials in the vacuum and zero gravityenvironment of space comprising:

an enclosed container for holding a sample of material to be melted;

said container being disposed between two clamping plates;

adjustable means extending between said plates for clamping said platesagainst said container;

a plurality of concentrically related enclosures surrounding saidcontainer;

a bolt connected to each of said plates, said bolts being aligned witheach other and extending outwardly and axially of said container andsaid furnace;

said bolts passing through opposite walls of said concentrically relatedenclosures;

spacers carried by said bolts between adjacent walls of saidconcentrically related enclosures;

electrical conducting means disposed in the vicinity of said enclosedcontainer for electrically heating a sample of material to be melted.

2. The invention as defined in claim 1 wherein the innermost of saidconcentrically related enclosures comprises an alumina crucible, saidelectrical conducting means comprising electric resistance wire, saidwire being arranged within said crucible.

3. The invention as defined in claim 2 wherein said crucible iscylindrical, a plurality of slots circumferentially spaced around eachend portion of said crucible, said resistance wire extending diagonallybetween opposite ends of said crucible and being supported in saidslots.

4. The invention as defined in claim 1 wherein said bolts are threadedlyjoined to said clamping plates in the center of said plates, saidspacers threadedly engaging said bolts.

5. The invention as defined in claim 4 wherein said plates and saidbolts are molybdenum.

6. The invention as defined in claim 1 wherein said concentricallyrelated enclosures comprise a plurality of cylinders having separableend covers, said cylinders and said covers comprising polished sheetmolybdenum.

7. The invention as defined in claim 1 wherein said enclosed containercomprises an interior carbon lining.

8. The invention as defined in claim 7 wherein said lining comprisesopposite spaced projections for supporting a sample of material prior tomelting of the material.

2. The invention as defined in claim 1 wherein the innermost of saidconcentrically related enclosures comprises an alumina crucible, saidelectrical conducting means comprising electric resistance wire, saidwire being arranged within said crucible.
 3. The invention as defined inclaim 2 wherein said crucible is cylindrical, a plurality of slotscircumferentially spaced around each end portion of said crucible, saidresistance wire extending diagonally between opposite ends of saidcrucible and being supported in said slots.
 4. The invention as definedin claim 1 wherein said bolts are threadedly joined to said clampingplates in the center of said plates, said spacers threadedly engagingsaid bolts.
 5. The invention as defined in claim 4 wherein said platesand said bolts are molybdenum.
 6. The invention as defined in claim 1wherein said concentrically related enclosures comprise a plurality ofcylinders having separable end covers, said cylinders and said coverscomprising polished sheet molybdenum.
 7. The invention as defined inclaim 1 wherein said enclosed container comprises an interior carbonlining.
 8. The invention as defined in claim 7 wherein said liningcomprises opposite spaced projections for supporting a sample ofmaterial prior to melting of the material.